Health maintenance, disease prevention, and diagnosis are performed via various prophylactic measures and diagnostic techniques. In the case of suspected tumor appearance, a patient can be subjected to invasive surgical procedures such as a biopsy of tissue. Another, noninvasive technique is tissue imaging using an imaging modality that may or may not require placement of a device near the suspected tumor and in contact with the patient's skin.
Biological imaging of living tissue involves radiation from the X-ray region through the microwave region of the electromagnetic spectrum. Techniques such as computed tomography (CT) and magnetic resonance imaging (MRI) provide a glimpse into structural features of tissue, and mathematical processing of two-dimensional data can render three-dimensional images of such tissue. Both hard and soft tissue can be imaged. Contrast agents allow improved resolution and enhancement of images as well as a means for imaging of cavities. For example, micro bubble contrast agents have been used in echocardiograms for cardiac shunt detection.
Imaging with non-ionizing radiation is preferred due to concerns over tissue damage and health effects of ionizing radiation. Further, many practitioners and patients seek to alleviate risk factors associated with certain contrast agents. However, some widely used imaging techniques have resolution and contrast insufficient to discover lesions and tumors at the on-set of growth. The art is always receptive to materials or methods that have enhanced resolution and image quality and that are also rich in information content.